usr/src/sys/tahoe/math/Kmodf.s

/*-
 * Copyright (c) 1985 The Regents of the University of California.
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Computer Consoles Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *      @(#)Kmodf.s     7.1 (Berkeley) 12/6/90
 */

#include "../tahoe/SYS.h"
#include "../math/fp.h"

/*
 *  float Kmodf (value, iptr, hfs)
 *  float value, *iptr;
 *  int hfs;
 *
 *  Modf returns the fractional part of "value",
 *  and stores the integer part indirectly through "iptr".
 */
        .text
ENTRY(Kmodf, R8|R7|R6|R5|R4|R3|R2)
 /*
 * Some initializations:
 */
        clrl    r3
        movl    4(fp),r0        /* fetch operand to r0. */
        movl    8(fp),r1
        movl    12(fp),r6       /* fetch addr of int to r6. */
 /*
  * get exponent
  */
        andl3   $EXPMASK,r0,r2  /* r2 will hold the exponent. */
        shrl    $EXPSHIFT,r2,r2
        subl2   $BIAS,r2        /* unbias it.  */
        jleq    allfrac         /* it's int part is  zero. */
        cmpl    r2,$56
        jgeq    allint          /* it's fraction part is zero. */
 /*
  * get fraction
  */
        movl    r0,r4           /* remember the original number. */
        movl    r1,r5
        bbc     $31,r0,positive /* if negative remember it. */
        incl    r3
positive:
                                /* clear the non fraction parts. */
        andl2   $(0!(EXPMASK | SIGNBIT)),r0
                                /* add the hidden bit. */
        orl2    $(0!CLEARHID),r0

        cmpl    r2,$HID_POS     /* see if there are bits to clear only in r0 */
        jgtr    in_r1           /* some bytes in r1     */
        jeql    onlyallr0       /* all r0 must be cleared. */
        mnegl   r2,r7           /* r7 - loop counter. */
        movl    $CLEARHID,r8    /* first bit to clear. */
1:
        andl2   r8,r0           /* clear int. bits from fraction part. */
        shar    $1,r8,r8
        aoblss  $0,r7,1b
1:
        andl2   r8,r4           /* clear frac bits for int calculation: */
        shar    $1,r8,r8
        cmpl    $0xffffffff,r8
        jneq    1b
        clrl    r5
        jmp     norm

onlyallr0:
        clrl    r0
        clrl    r5
        jmp     norm

in_r1:
        clrl    r0
        subl3   r2,$HID_POS,r7
        movl    $0x7fffffff,r8
1:
        andl2   r8,r1
        shar    $1,r8,r8
        orl2    $0x80000000,r8
        aoblss  $0,r7,1b
1:
        andl2   r8,r5
        shar    $1,r8,r8
        cmpl    $0xffffffff,r8
        jneq    1b
norm:
        addl2   $BIAS,r2        /* fnorm expects it biased. */
        pushl   16(fp)          /* hfs */
        callf   $8,_Kfnorm      /* normelize fraction part. */
        cmpl    $0,r0
        jeql    1f
        bbc     $0,r3,1f
        orl2    $0x80000000,r0
1:
        movl    r4,(r6)         /* put int part in place. */
        movl    r5,4(r6)
        ret

allint:
        movl    r0,(r6)         /* copy the argument to the int addr. */
        movl    r1,4(r6)
        clrl    r0              /* clear the fraction part. */
        clrl    r1
        ret

allfrac:
                                /* the fraction is ready in r0. */
        clrl    (r6)            /* zero the int part. */
        clrl    4(r6)
        ret

ret_zero:
        clrl    (r6)
        clrl    4(r6)
        clrl    r0
        clrl    r1
        ret